Develop Reference

How to know if Android resolved to use a localized strings.xml file or the default one?

The motivation of this question comes from this other question:
How do I get the current language my app is in? (Not the device's language as specified in the Settings. I want the language that Android resolved to use for my app).
This question has been asked several times on the site, but it fails to consider this corner-case:
Imagine the user has only one preferred language in his device: say German, for example.
My app two strings.xml files: The default one, and one in French (values-fr/strings.xml).
Obviously, Android will resolve to use the default strings.xml in this case.
But if I do any of the following, it will return German:
Locale.getDefault()
getResources().getConfiguration().getLocales().get(0)
getResources().getConfiguration().locale.
(And many other suggestions that I have found on the site)
And who told Android that the default strings.xml file was in German? Why did it made that assumption? The default file could be in Spanish, Italian, Polish...whatever.
Ideally, I would like a method that returns null in this case. Some method that tells me that no match was found for German and Android had to fall-back to the default strings.xml.
Does such method exist?

Put the language name in both strings.xml files. For example, as languageName.
When you get the string for R.string.languageName, it will be the language chosen by Android among the ones you support.

Those functions all return the phone's locale. They have nothing to do with resource localization. So nobody said the strings.xml file was German. The user set the phone to German, and the resource subsystem decided strings.xml was the best match for that. Basically you have the way it works backwards.
I don't think there is a way to get what you want for two reasons:
1)It's supposed to be transparent to the programmer.
2)It doesn't pick one file over the other. It picks independently for each string. So if you have a strings.xml with two strings A and B, and had a german strings file with only A, it would give you the german A and the default B.

Catalan and Basque strings in Android not being used [duplicate]

When you want to add locale-specific resources in Android, you have to add the lowercase ISO-3166-1 code of the language to the resource folder's name. So far so good.
Now I want to add Catalan and Basque strings to my application. According to the ISO list, I would have to add values-ca and values-eu. But will that work, actually?
Edit: With a custom language chooser in your app, you can provide support for languages even when they're not in the device's settings menu. I've made the library that I use for this available on GitHub:
https://github.com/delight-im/Android-Languages
I don't know if Android supports all ISO codes and if these "minor" languages will be displayed at all. If Android is not available in these languages, perhaps the device will not even recognize this language as its default locale and just use es for Spanish.
Can someone help?

Many devices ship with a limited selection of languages in the settings menu, but can actually be set to any system locale using an app such as LocaleSwitch.
It should be pretty easy to test whether Basque is supported by adding a custom locale in LocaleSwitch and then adding the resource folder to see if the system loads the resources from this folder automatically.
Finally, Gingerbread 'support' for Catalan may only reference the inclusion of android.R values since 2.3, though I can't see them in the framework repository.

Actually not all languages are documented at Android docs and many brands did your custom version of Android which may change its list, but be sure that if a device has Catalan and/or Basque suports it will use ISO standard, and the values will got rigth as it is converted with string comparision.
Maybe it would be a good choice to put a handed changer if you got that most devices do not have this support on your tests.

The thing is, if the language is not listed in the language selection list on the device, the resources can never be used as the device can never be put in this configuration by the user.
On the other hand, if the device allows you to select Basque, it will be using this format, and your resources will be used.

We can now create our "values-eu-rES" folder and have our app in Basque, Android Lollipop has made it.

We can create a folder
Basque strings ->
value-eu [Basque]
another folder
Catalan strings ->
value-ca [Catalan]

Adding a new language in LocaleSwitch, you need to type the ISO 639-1 code. For instance, if you want to switch to basque you need to enter "eu". Afterwards, you will see the new locale as "vasco".
That makes me think that basque locale is supported by android.

How to Properly Support English when Localizing an App?

I'm working on localizing an Android app.
For arguments sake, let's say the app will support English, Albanian, and Bengali.
Currently all English strings are listed in the "default value" column of the translations editor:
Apps on the app store generally state what locales they support.
I'm assuming when you submit an app that either a person or machine verifies your claims... so...
Is it necessary to explicitly add English (en) locale/column in addition to the default values (just as Albanian and Bengali have been added in the photo) in order for the app to be considered to officially "support" English?

You do not have to add English locale to have it in Supported Language menu. Check documentations out.
When your Java code refers to strings, the system would load strings from the default (en_US) resource file, even if the app has Spanish resources localized under es_ES. This is because when the system cannot find an exact match, it continues to look for resources by stripping the country code off the locale. Finally, if no match is found, the system falls back to the default, which is en_US.
The system would also default to en_US if the user chose a language that the app didn't support at all, like French.
Default locale is en_US.

No.
Apps on the app store generally state what locales they support.
If you are talking about Apple's App Store, Google Play won't list the supported languages in similar fashion.
However, you can localize the store listing page. According to play console help, If a user's language preference matches the translation languages you've added, they'll see your app's translated version. You can also add localized graphic assets for your store listing pages. See this for more. This feature is similar to App Store's metadata localization.

There is an easy solution to your problem.
Just find the path in your project:
res/
and add a folder named:
values-en
Then add a file named:
strings.xml
Finally, it will look like this:
res/values-en/strings.xml
And the resources in it will show when the user's language setting is English.

Android programmatically check if app is localized for a language

I have an app that needs to provide strings localized in the language of another device. As soon as my app knows the language of the other device it creates a new Resources class. Similar to this question.
The resource object just created can fall back when getting strings if the language is not supported (assume other device is set to en_US):
values-en-rUS/strings.xml
values-en/strings.xml
values/strings.xml
Instead of the third fallback I want to fall back to the language of my own device (assume my device is set to es_ES it would then be):
values-en-rUS/strings.xml
values-en/strings.xml
values-es-rES/strings.xml
values-es/strings.xml
values/strings.xml
I could achieve that very easy if I could programmatically check if a language/region is supported by my app. Found this AssetManager.getLocales() but think it doesn't help.
Is there a way to achieve the desired fallback or a way to check if the app is localized in a specific language/region?

See here. Tested it and got the correct device locale as a two sign string. Code is:
String Language = Locale.getDefault().getLanguage() //returns eg. "de" for german

How does Android handle unsupported languages?

I've made an app that runs in multiple languages, but if the user runs it in an unsupported language, will it display the main one?
If it is the case, how can I make it display in English instead?

You are right.
Just put your english strings on the strings.xml file, so it will be loaded by default if no other language matches the phone lang.
Hope this helps.

if the user runs it in a not supported language, will it display the main one?
The default language, yes See the docs for detailed information.
Whenever the application runs in a locale for which you have not provided locale-specific text, Android will load the default strings from res/values/strings.xml. If this default file is absent, or if it is missing a string that your application needs, then your application will not run and will show an error.
how can I make it to display English instead?
Also see the docs for that, you should use english in the default strings.xml
How to Create Default Resources
Put the application's default text in a file with the following location and name:
res/values/strings.xml (required directory)
The text strings in res/values/strings.xml should use the default language, which is the language that you expect most of your application's users to speak.

Depends really what language are you using in your string.xml (main one). If there is no language case for what the user selects in the Settings, the app will load in the default values from the strings.xml

Language which you want to load by default then put that strings.xml
in values
folder without any suffix with values folder

In fact when you run your app, the app will check if the locale is available thanks to the string.xml contains in the value-locale folder. If nothing is found the string.xml in values is used so just put english traduction in your string.xml.
I hope to be clear.